A variable speed control system is known which includes a multiple-speed transmission which changes an output of an engine in a multiple stages based on a change in meshing state of a dog clutch which is caused in association with an operation of a change pedal which is mechanically connected to the multiple-speed transmission, a pedal load detection device which detects an operation load of the change pedal, and a control unit which permits a speed change action of the multiple-speed transmission according to the change pedal by suppressing or shutting off the engine output to the multiple-speed transmission when a change pedal operation load detected by the pedal load detection device exceeds a predetermined threshold.
For example, patent literature 1 discloses a variable speed control system which permits a speed change action of a multiple-speed transmission according to a change pedal by shutting off an engine output to the multiple-speed transmission through disengagement of a main clutch when a change pedal operation load detected by a strain sensor exceeds a preset threshold. With a change speed control system like this, it is possible for the multiple-speed transmission to perform a speed change action only by operating the change pedal without operating a clutch lever.